<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒子模型</title>
    <style>
        div{
            width: 200px;
            height: 200px;
            border: 1px solid red;
        }
        #d1{
            /*margin-left: 100px;*/
            /*margin-top: 100px;*/
            /*四个方向全是100px*/
            /*margin: 100px;*/
            /*上下100px，左右200px*/
            /*margin: 100px 200px;*/
            /*上右下左 顺时针赋值*/
            margin: 100px 200px 30px 400px;
        }
        #d2{
            border-left: 10px dotted red;
            border-radius: 30px;
        }
        #d3{
            /*padding*/
            padding: 100px;;
        }
    </style>
</head>
<body>
    <div id="d1" >测试外边距</div>
    <div id="d2">测试边框</div>
    <div id="d3">测试内边距</div>
    <div>测试内容</div>
</body>
</html>